Using it, people with Android and iOS can exchange messages with friends and colleagues using the BBM system. The system notifies users when each message has been read and indicates when someone is in the process of responding. Files and photos can also be shared over BBM.

There are around 60 million active monthly users of BBM.

The launch of BBM on Android and iOS is about more than just making it easy for people to message Blackberry users.

"We intend to be the leading private social network for everyone who needs the immediate communication and collaboration of instant messaging combined with the privacy, control and reliability delivered through BBM," said Andrew Bocking, Blackberry's executive vice president for BBM, in a statement.

But to do that, Blackberry is up against stiff competition from companies like Yahoo, AOL and Google, which have operated open instant messaging networks for years. It will not only have to convince people of their need for a new platform and to download the app, but it will also have to get people used to exchanging a BBM "PIN," an alphanumeric code each user has that identifies them, instead of their email address.

Blackberry has struggled to keep a foothold in the competitive smartphone market ever since it delayed an update to its OS. Over the last few years, the company's handsets didn't keep up with innovations in the market.

That changed earlier this year with the launch of Blackberry's OS 10, which was critically praised. But the earlier delay now has Blackberry battling a perception that it's an also-ran in the market.

Earlier this year, Blackberry said it was exploring its options and has been in talks with several parties that are interested in acquiring the company.